JP2005324245A - Liquid phase diffusion joining method for metal machine parts, and metal machine parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid phase diffusion joining method for metal machine parts, which method can shorten a joining time compared with a conventional liquid phase diffusion joining method, and can improve the quality/reliability of a joint, such as the uniformity of a joining structure, the tensile strength, the fatigue strength, compared with a conventional resistance welding method, and is excellent in the quality of a joint portion and the productivity, and further to provide the metal machine parts assembled using the method. <P>SOLUTION: In the liquid phase diffusion joining method for the metal machine parts, an amorphous alloy foil for the liquid phase diffusion joining is placed in the groove face of a metallic material. In a primary joining, a joint portion is formed by pressure joining of the amorphous alloy foil and the metallic material fused by the resistance welding. Next, in a secondary joining, after the joint portion has been heated again over the melting point of the amorphous alloy foil, the solidifying process of the joint portion is completed by keeping the temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a metal machine part and a metal machine part, and more particularly, to a liquid phase diffusion bonding method and a metal machine part for a metal machine part used for automobile parts and the like.

  Conventionally, a welding method has been mainly used as a method for joining metal materials, but in recent years, the application of a liquid phase diffusion joining method is becoming widespread as a new industrial joining technique.

  In the liquid phase diffusion bonding method, an amorphous alloy foil having a low melting point compared to the material to be bonded, specifically, 50% or more of the crystal structure is non-between the bonding surfaces of the material to be bonded, that is, between the groove surfaces. After interposing a multi-element alloy foil containing a Ni or Fe base material containing an element, for example, B or P, which is crystalline and has an ability to form a joint joint through a diffusion-controlled isothermal solidification process, In this technique, the joint is heated and maintained at a temperature equal to or higher than the melting point of the amorphous alloy foil to form the joint in the isothermal solidification process.

  This liquid phase diffusion bonding method can be joined with lower heat input than ordinary welding methods, so there is almost no residual stress in the weld due to thermal expansion and contraction. Since there is no surplus, the joining surface is smooth and a precise joining joint can be formed.

  In particular, since liquid phase diffusion bonding is surface bonding, it is completely different from conventional welding methods in that the bonding time is constant without depending on the area of the bonding surface and the bonding can be completed in a relatively short time. This is the concept of joining technology. Therefore, if the joint can be held for a predetermined time at a temperature equal to or higher than the melting point of the amorphous alloy foil inserted between the groove surfaces of the material to be bonded, it is possible to realize the bonding between the surfaces without selecting the groove shape. Have.

  The present applicant has already proposed in Patent Document 1 and Patent Document 2 a method of manufacturing a metal mechanical part having a pipe line inside using this liquid phase diffusion bonding method.

  However, although the liquid phase diffusion bonding disclosed in Patent Document 1 and Patent Document 2 has a relatively short bonding time, the diffusion atoms in the amorphous alloy foil are connected to each other as long as the isothermal solidification progresses at the diffusion rate. In order to diffuse and dissipate into the material to be joined by an amount sufficient to raise the melting point of the alloy, it corresponds to a temperature equal to or higher than the melting point of the alloy foil when an amorphous alloy foil having a thickness of 10 μm is used. It is necessary to keep isothermal at about 900-1300 ° C. for about 60 seconds or more.

  Although it is possible to reduce the bonding time to some extent by reducing the thickness of the amorphous alloy foil used for liquid phase diffusion bonding, it is possible to reduce the bonding defects and joint strength due to the processing accuracy of the groove surfaces to be bonded. Since the influence on the deterioration of the alloy becomes large, there is a limit to the reduction in the thickness of the alloy foil. In fact, the alloying foil for bonding induces the base material to melt at the time of joining by increasing the concentration of diffusion atoms due to the melting point drop of the joining foil or depending on the chemical composition of the material to be joined. The thickness of a typical bonding alloy foil often exceeds 50 μm.

  Also, by increasing the pressure stress in liquid phase diffusion bonding, it is possible to shorten the bonding time to a certain extent, but by increasing the pressure stress, buckling deformation of the materials to be joined is likely to occur. For this reason, there is a limit to the increase in pressure stress.

  Therefore, in the method of manufacturing a metal machine part using the liquid phase diffusion bonding disclosed in Patent Document 1 and Patent Document 2, the liquid phase diffusion is performed to improve the productivity of the metal machine part and reduce the manufacturing cost. It has been an industrial problem to shorten the joining time as compared with the prior art while maintaining the joint quality of the joint.

  On the other hand, an electric resistance welding method is known as a joining technique that has been widely used for joining metal mechanical parts.

  The electric resistance welding method is a method of forming a joint joint by using a resistance heating generated by applying an electric current to a metal and applying a large current to press the groove while melting the groove of the material to be joined instantaneously. .

  For example, when welding a thermocouple to a temperature-measured body for temperature measurement or joining a steel plate to an automobile frame material, when the joint area is relatively small and high joint strength is not required, spot welding, projection, etc. Electrical resistance welding methods such as welding and upset welding are often used as simple joining methods, and conversely, when joining grooves with a relatively large joint area, Continuous electric resistance welding is used for seam welding of metal steel pipes.

  However, when metal mechanical parts are manufactured using these resistance weldings, the so-called joint defects due to residual oxide inclusions at the joints or the so-called welding current shortage due to fluctuations in joining conditions, for example. A welding defect called “cold welding” due to insufficient melting may occur. In addition, large deformation occurs due to pressurization at the time of joining, and fine cracks are generated in the welded part, or the open tip part remains in an unjoined state, which causes a decrease in joint performance, particularly fatigue strength. It was. Particularly when at least one of the cylindrical metal materials is a material to be welded, there is a tendency for the joint fatigue strength to decrease significantly. As countermeasures for this, conventionally, for example, for changing the material design or improving the weld shape Post-processing was required, and there were problems such as restrictions on the degree of freedom in joint design and increased costs.

  In addition, the joint width is extremely narrow in resistance welding, and groove deformation may occur. Therefore, it is difficult to guarantee the quality by nondestructive inspection. However, improving the joint quality in resistance welding is an industrial technical problem.

  Further, Patent Document 3, Patent Document 4 and Patent Document 5 disclose a method of joining metal members by using both liquid phase diffusion bonding and current-resistance resistance welding in joining an Al-based cylinder head body and an Fe-based valve seat. However, all of them are merely resistance welding with a brazing filler metal interposed between them for primary bonding only.

  That is, since the isothermal solidification diffusion treatment for making the non-isothermal solidification structure of the resistance welded portion generated in the primary joining in the methods disclosed in Patent Documents 3 to 5 into the liquid phase diffusion bonding structure is not performed, the quality of the joint portion It is difficult to improve sufficiently.

  Further, in the above-described technique, the brazing filler metal is discharged under pressure until it becomes extremely thin, but this is regarded as a manufacturing process, and therefore, the homogenization of the joint structure is not considered. Furthermore, these disclosed technologies are joint forming technologies for joining different materials of Fe and non-ferrous metals such as Al, and there is no description about joining of steel materials, particularly iron base materials. Originally, normal welding can be applied between iron-based materials, and it is difficult to apply normal welding technology for joining dissimilar joints. Therefore, techniques for joining iron-based materials are described in the above-mentioned patent documents. Not.

Japanese Patent Application No. 2001-384765 JP 2001-321963 A JP-A-11-90619 Japanese Patent Laid-Open No. 11-90620 Japanese Patent Application Laid-Open No. 11-90621

  In view of the above-described problems of the conventional technology, the present invention can shorten the bonding time compared to the conventional liquid phase diffusion bonding method, and can make the joint structure more uniform than the conventional resistance welding method. We provide improved joint quality and reliability such as tensile strength and fatigue strength, and provide liquid phase diffusion bonding methods for metal machine parts with excellent joint quality and productivity, and metal machine parts assembled using them. For the purpose.

The present invention has been made to solve the above-described problems, and the gist thereof is as follows.
(1) An amorphous alloy foil for liquid phase diffusion bonding is interposed on the groove surface of the metal material, and the amorphous alloy foil and the metal material are melt-welded by resistance welding as a primary bonding, and the joint portion Then, as the secondary bonding, the joint portion is reheated to a temperature higher than the melting point of the amorphous alloy foil, and then held and liquid phase diffusion bonding is performed to complete the solidification process of the joint portion. A liquid phase diffusion bonding method for metal machine parts.
(2) The liquid phase diffusion bonding method for metal machine parts according to (1), wherein the holding time after the reheating is 30 seconds or more.
(3) The composition of the amorphous alloy foil is based on Ni or Fe, and contains 0.1 or 20.0 atomic% of one or more of B, P and C as diffusion atoms, respectively. Furthermore, the liquid phase diffusion bonding method for metal machine parts according to (1) or (2), further comprising 0.1 to 10.0 atomic% of V.
(4) The resistance welding is a welding method of any one of current welding type spot welding, projection welding, upset welding, and flash butt welding, and the amorphous alloy foil by the resistance welding. The method of liquid phase diffusion bonding of metal machine parts as set forth in any one of (1) to (3), wherein the time of melt pressure welding between the metal material and the metal material is 10 seconds or less.
(5) The liquid phase diffusion bonding method for metal machine parts according to any one of (1) to (4), wherein the amount of current in the resistance welding is 100 to 100,000 A / mm @ 2.
(6) In any one of (1) to (5), the applied pressure in the fusion welding between the amorphous alloy foil and the metal material by the resistance welding is 10 to 1000 MPa. The liquid phase diffusion bonding method of the metal mechanical component as described.
(7) The thickness in the pressing direction of the non-isothermal solidified structure in the cross-sectional structure of the joint portion formed by the resistance welding is 10 μm or less on average and any one of (1) to (6) A liquid phase diffusion bonding method for metal mechanical parts as described in 1 above.
(8) The liquid phase of the metal machine component according to any one of (1) to (7), wherein the joint efficiency of the joint portion formed by the resistance welding is 0.5 to 2.0. Diffusion bonding method.

However, the joint efficiency is the ratio of the area of the groove surface of the metal material to the area of the joint part after the amorphous alloy foil and the metal material are melt-welded.
(9) Any one of (1) to (8), wherein after the solidification process of the joint portion is completed, the joint structure is controlled by cooling at a cooling rate of 0.1 to 50 ° C./second. A liquid phase diffusion bonding method for metal mechanical parts as described in 1 above.
(10) A metal machine part composed of a joint portion formed by liquid phase diffusion bonding with a metal material, wherein the maximum grain size of the old γ crystal in the metal structure as-bonded of the metal machine part is 500 μm or less Metal machine parts.
(11) At least one of the metal materials is a cylindrical metal material, and the cylindrical metal material with respect to the butt contact is formed when the end of the cylindrical metal material and the other metal material surface are butted to perform the primary joining. The cylindrical metal material end so that the inner surface side groove height A, the outer surface side groove height B, and the distance C from the butt contact to the outer periphery satisfy the following expression (1): A V-shaped groove is formed in the part, and the liquid phase diffusion bonding method for metal machine parts according to any one of (1) to (10).

0.2 ≦ B / A ≦ 1 and C / t ≦ 0.5 (1)
Where A is the groove height on the inner surface side of the cylindrical metal material, B is the groove height on the outer surface side of the cylindrical metal material, C is the distance from the butt contact point of the cylindrical metal material to the outer periphery, and t is the cylindrical metal material Indicates the thickness of each material.
(12) The liquid phase diffusion bonding of metal machine parts according to (11), wherein the maximum remaining height at the open tip after the primary bonding is not more than three times the thickness of the amorphous alloy foil. Method.
(13) The liquid phase diffusion bonding method for metal machine parts according to (11) or (12), wherein the joint efficiency after the primary bonding is 0.8 or more.
(14) The liquid phase diffusion bonding of metal machine parts according to any one of (11) to (13), wherein the maximum remaining height of the open tip portion after the secondary bonding is 70 μm or less. Method.

As described above, according to the present invention, when manufacturing a metal part by forming a joint using liquid phase diffusion bonding, an amorphous alloy foil for liquid phase diffusion bonding is interposed between the grooves of the metal material. As the primary bonding, the amorphous alloy foil is melt-welded by resistance welding to provide a very thin bonding alloy layer formed by melting and solidifying the amorphous alloy foil. It has good mechanical properties such as homogeneity of structure, tensile strength, toughness, fatigue strength, etc. by applying an isothermal solidification process of post-liquid phase diffusion bonding at a reheating temperature above the melting point of You can get fewer joints.
As a result, metal parts having high joint quality and high reliability can be manufactured with high productivity. In addition, regarding the fatigue strength of the joint joint, at least one of which is made of a cylindrical metal material, which has been a problem in the conventional resistance welding method, fine cracks in the welded portion are caused by the interaction between the primary joint and the secondary joint of the present invention. It is possible to reduce occurrence, reduce the unbonded remaining amount of the open tip portion, and manufacture a joint excellent in fatigue strength and a metal machine part thereby.

  The present invention provides a high-productivity and low-cost metal machine part that cannot be manufactured by conventional machining, grinding, and drilling, and a high-cost metal machine part that has low productivity and low material yield. It provides welding technology for completely new metal machine parts that can be manufactured at the same time, and can greatly contribute to the functional improvement and supply of metal machine parts that can be achieved by applying liquid phase diffusion bonding. In particular, in the manufacture of hollow parts such as camshafts conventionally produced by casting, forging, etc., shafts used for various prime movers, or conventional metal machine parts using a single liquid phase diffusion bonding method, the present invention By applying the method, effects such as reduction in manufacturing cost, improvement in productivity, and improvement in quality of the joint are expected, and the industrial contribution by the present invention is great.

  Details of the present invention will be described below.

  In the method of the present invention, a metal material is used as a material to be joined, and after abutting with an amorphous alloy foil for liquid phase diffusion joining between the groove surfaces formed at the end of the metal material, the primary joining is performed. The amorphous alloy foil and the metal material are melt-welded by resistance welding to form a joint portion.

  In this primary joining, for example, an electrode for supplying a welding current to the groove surface (butting surface) of the materials to be joined and heating and melting them is disposed on each material to be joined, and the stress required for pressure welding is applied between the groove surfaces. A resistance welding apparatus to which a stress applying mechanism for loading, for example, a hydraulically operated Instron type tension / compression apparatus is applied is used.

  In this primary joining, the groove surface of the material to be joined and the alloy foil for liquid phase diffusion bonding are melted by resistance heat welding heat input, and the oxide and groove formed during heating and melting are upset by the pressure stress. The extraneous matter present on the surface is discharged out of the joint surface together with the molten metal.

  In primary bonding, the amorphous alloy foil for liquid phase diffusion bonding inserted between the groove surfaces of the material to be bonded has a lower melting point than the steel material as the material to be bonded, and the volume of the foil An amorphous alloy foil having an amorphous structure of 50% or more is used.

  Compared to the material to be joined at a temperature of about 900 to 1200 ° C. between the groove surfaces of the material to be joined, a liquid phase diffusion bonding alloy foil having a low melting point is interposed and melt-welded by resistance welding, so that the liquid phase is applied to the groove surface. The diffusion bonding alloy foil is uniformly melted, and at the same time, the effect of discharging the oxide generated by heat melting and the extraneous matter remaining on the groove surface together with the molten metal to the outside of the bonding surface is promoted.

  The composition of the amorphous alloy foil for liquid phase diffusion bonding in the present invention is based on Ni or Fe, and one or more of B, P and C as diffusion atoms is 0.1. It contains ˜20.0 atomic%, and further contains 0.1 to 10.0 atomic% of V having an effect of lowering the melting point of the oxide generated between the joint surfaces during the primary joining. Is preferred.

  B, P, and C in the alloy foil for liquid phase diffusion bonding are used as diffusion elements for realizing isothermal solidification necessary for achieving liquid phase diffusion bonding as secondary bonding, or have a melting point higher than that of the material to be bonded. In order to sufficiently obtain its action, it is necessary to contain 0.1 atomic% or more, but if added excessively, a coarse boride, metal compound, or Since carbides are generated and the joint strength is reduced, the upper limit is preferably made 20.0 atomic%.

V in the alloy foil for liquid phase diffusion bonding reacts instantaneously with the oxide or residual oxide (Fe ₂ O ₃ ) generated between the groove surfaces during resistance welding as primary bonding, and low melting point composite oxide ( V ₂ O ₅ —Fe ₂ O ₃ , melting point: about 800 ° C. or less), melting and discharging low melting point composite oxide together with molten metal by pressure stress during resistance welding, and oxidizing the joint The effect of reducing material inclusions can be obtained. In order to sufficiently obtain this action and effect, it is preferable to contain 0.1 atomic% or more of V. On the other hand, when V is added excessively exceeding 10.0 atomic%, the number of V-based oxides increases and the residual oxides increase, and the melting point of the alloy foil for liquid phase diffusion bonding is increased. In order to make liquid phase diffusion bonding as bonding difficult, the upper limit is preferably 10.0 atomic%.

  In addition, as the resistance welding used as the primary joining in the present invention, any one of a welding method of an electric heating type spot welding, projection welding, upset welding, and flash butt welding is used. In general, spot welding, projection welding, and upset welding are suitable for joining when the joining area is relatively small and does not require high joining strength, and flash butt welding can apply high pressure with a large current. This is suitable for joining a groove having a large joining area. The selection of these resistance welding methods is not particularly limited, and is selected in a timely manner according to the characteristics of each welding method, the required characteristics of the joint and the welding conditions, and the welding time is 10 seconds or less in order to improve productivity. Is preferable.

In addition, the welding heat input of resistance welding in the primary joining is a current density of 100 A / mm ² or more in order to melt the grooved surface and the amorphous alloy foil for liquid phase diffusion bonding between the grooved surfaces in a short time. On the other hand, if the current density is increased excessively, the molten metal of the amorphous alloy foil is disturbed, and it becomes difficult to uniformly distribute the groove surface with a predetermined thickness. 000 A / mm ² or less is necessary. Therefore, the current density of resistance welding is preferably 100 to 100,000 A / mm ² .

  Also, the pressure stress of resistance welding in primary bonding reduces the thickness of the bonded alloy layer formed by melting and solidifying the amorphous alloy foil for liquid phase diffusion bonding between the groove surfaces to 10 μm or less. In order to shorten the bonding time of the liquid phase diffusion bonding as the secondary bonding, 10 MPa or more is necessary. On the other hand, when the pressure stress is excessively high, deformation of the joint is generated, so it is necessary to set the pressure to 1000 MPa or less. is there. Therefore, the pressure stress in resistance welding is preferably 10 to 1,000 MPa. Since the degree of deformation of the joint is changed by the Young's modulus at the welding temperature of the material to be joined, it is more preferable to adjust the upper limit of the pressure stress depending on the material of the material to be joined.

  Furthermore, the joint efficiency of the joint portion formed by resistance welding in the primary joining (area of the groove surface of the steel material / area of the joint portion after the melt welding of the amorphous alloy foil and the steel material) is the shape of the groove Considering the joint restraint effect after joining due to the joint, 0.5 or more is necessary to ensure the joint's static tensile strength equal to or higher than that of the base metal, and high resistance during resistance welding. Considering the case where the joint area is larger than the cross-sectional area of the base material as a result of swelling of the joint portion due to the pressure stress, the upper limit is preferably set to 2.0 in order to obtain good joint characteristics.

  By the primary bonding shown above, the amorphous alloy foil for liquid phase diffusion bonding inserted between the groove surfaces of the materials to be bonded is melt-welded in a short time, so that the amorphous alloy is melted and solidified. An extremely thin bonding alloy layer can be formed. In the experiment by the present inventors, from the observation result of the joint cross-sectional structure by the optical microscope, the thickness of the bonded alloy layer composed of the structure obtained by melting and solidifying the amorphous alloy foil obtained by the primary bonding is a maximum of 7 μm or less, the average It has been confirmed that the thickness is 3 μm or less.

  The bonding alloy layer formed by melting and solidifying the extremely thin amorphous alloy for liquid phase diffusion bonding in this way is equal to or higher than the melting point of the amorphous alloy foil in the liquid phase diffusion bonding as the subsequent secondary bonding. The isothermal solidification is substantially completed by holding for about 15 seconds at a temperature of about 30 seconds, and if it is held for about 30 seconds, a complete isothermal solidification structure can be obtained when carbon steel is normally used as the material to be joined. Is confirmed by calculation and experiments using a diffusion equation.

  FIG. 1 shows an alloy layer formed by melting and solidifying an amorphous alloy foil for liquid phase diffusion bonding (in the case of the present invention, an alloy layer after primary bonding, in the case of the conventional method, an alloy after pressure melting) FIG. 5 is a diagram showing the relationship between the thickness of the layer) and the holding time until the isothermal solidification of the alloy layer is completed (the holding time until the non-isothermal solidified structure cannot be observed).

  In the conventional liquid phase diffusion bonding method, it is possible to reduce the thickness of the alloy layer formed by melting and solidifying the amorphous alloy foil for liquid phase diffusion bonding to an extent by increasing the applied pressure. Since joint deformation occurs due to an increase in pressure, it is difficult to reduce the thickness of the alloy layer to 10 μm or less as shown in FIG. 1, and the holding time until the isothermal solidification of liquid phase diffusion bonding is completed is 100. Needed more than a second. If the isothermal solidification holding time is set to 100 seconds or less by the conventional method, the non-isothermal solidified structure of the amorphous alloy foil remains in the bonded alloy layer, and characteristics such as joint strength and toughness are the base material. There arises a problem that it is remarkably reduced as compared with the above.

  On the other hand, in the method of the present invention, the average thickness of the bonded alloy layer formed by melting and solidifying the amorphous alloy foil for liquid phase diffusion bonding is reduced to 7 μm or less by primary bonding (resistance welding). The subsequent holding time until the isothermal solidification of the liquid phase diffusion bonding is completed by the secondary bonding (liquid phase diffusion bonding) (the non-isothermal solidification structure of the bonded alloy layer completely disappears) is reduced to 30 seconds or less. It can be shortened. In the experiments of the present inventors, as shown in the figure, it was confirmed that the average thickness of the bonded alloy layer can be reduced to 3 μm by primary bonding (resistance welding). In this case, secondary bonding (liquid phase diffusion) It can be expected that isothermal solidification is completed with a holding time of 15 seconds (completely disappearing of the non-isothermal solidified structure of the bonded alloy layer). From the above, it can be expected that the method of the present invention significantly reduces the bonding time while maintaining the same or better joint quality as compared with the conventional liquid phase diffusive bonding, and improves the productivity.

  FIG. 2 is a diagram showing the relationship between the isothermal solidification holding time and the joint strength in secondary bonding (liquid phase diffusion bonding) according to the method of the present invention.

  The joint joint strength was expressed as the ratio of the tensile strength of the joint joint to the tensile strength of the base material when the tensile test was performed in the direction in which the joint was pulled away from the joint surface. When this value is 1, it means that the base material is broken, and when it is 1 or less, it means that the joint is broken.

  In actual bonding, the thickness of the bonding alloy layer formed by melting and solidifying the amorphous alloy foil for liquid phase diffusion bonding formed on the groove surface by primary bonding (resistance welding) of the present invention is Although the variation occurs depending on the position of the surface, it can be seen from FIG. 2 that when the isothermal solidification holding time in the secondary bonding (liquid phase diffusion bonding) is at least 30 seconds or more, the tensile test result of the joint becomes the base material fracture, Good joint strength higher than tensile strength can be obtained.

  In the method of the present invention, based on the above experimental results, the isothermal solidification holding time of the secondary bonding (liquid phase diffusion bonding) is set to 30 seconds or more in order to ensure a joint strength equal to or higher than that of the conventional liquid phase diffusion bonding method. Is preferred.

  In addition, the isothermal solidification holding time of the secondary bonding (liquid phase diffusion bonding) increases and a predetermined joint strength can be stably obtained. However, if the isothermal solidification holding time is excessively increased, the metal structure of the joint is increased. Since the old γ crystal grain size becomes coarse and the toughness of the joint decreases, the upper limit is more preferably 100 seconds or less.

  In the present invention, after the secondary joining, that is, after the isothermal solidification of the liquid phase diffusion joining is completed, the desired metal structure such as carbon steel can be obtained by controlling the cooling rate according to the steel type of the material to be joined. For example, a metal structure such as ferrite + pearlite, ferrite, bainite, martensite, etc. can be obtained, and if it is austenitic steel, it has a good metal structure due to the action of re-dissolving inclusions such as precipitates generated during bonding A joint can be obtained.

  In the present invention, in order to ensure the minimum required low-temperature transformation structure (bainite or martensite) ratio for improving the strength and toughness of joints required for machine parts for automobiles, The cooling rate after completion of isothermal solidification of phase diffusion bonding is preferably 0.1 ° C./second or more. Excessive cooling causes a decrease in toughness and ductility, so the upper limit of the cooling rate is 50 ° C. / The second is preferred. By controlling the cooling rate, even a ferritic steel, austenitic steel, or a dissimilar joint between ferritic steel and austenitic steel can form a healthy and highly compatible joint.

  In the method of the present invention, after the cooling described above, for the purpose of further tempering the metal structure, heat treatment such as reheating and quenching, tempering, quenching + tempering, etc. may be repeated alone or multiple times. In this case, the joint structure can be further homogenized and the effect of the present invention can be further enhanced.

  In addition, a deep cooling process is also effective in the material which repels a retained austenite, and can suppress the deformation | transformation by aging.

  According to the embodiment of the present invention described above, the amount of deformation of the joint can be reduced as compared with the conventional single resistance welding method, and normal machining such as drilling, cutting, cutting, etc. is performed when assembling metal machine parts. Applicable to the assembly of machine parts with shapes that cannot be machined even with full use, or machine parts that contain dissimilar joints of difficult-to-combine materials that are difficult to combine, and machine parts that cause a significant increase in material costs due to machining. It is possible to improve productivity and reduce costs at the same time. Further, according to the embodiment of the present invention, even when a minute crack occurs on the joint surface after the primary joining (resistance welding), the unmelted amorphous alloy foil is further melted by the subsequent secondary joining (liquid phase diffusion joining). It is possible to repair minute cracks by flowing into the cracks, and to obtain an effect of changing the alloy layer from the non-isothermally solidified structure to a completely isothermally solidified structure. A joint with high quality and excellent quality can be obtained.

Further, according to the embodiment of the invention, the isothermal solidification retention time of the amorphous alloy foil, that is, the joint joint is made of an amorphous alloy while maintaining the joint quality equal to or higher than that of the conventional single liquid phase diffusion joining method. Since it is possible to significantly reduce the time for holding at the reheating temperature above the melting point of the foil, it is possible to greatly suppress the coarsening due to the growth of the crystal grain size in the isothermal solidification holding of the joint joint compared to the conventional case. . As a result, the metal mechanical component consisting of the steel material assembled by the method of the present invention and the joint formed by liquid phase diffusion bonding has a maximum grain size of the old γ crystal in the as-bonded metal structure as small as 500 μm or less. The toughness can be improved as compared with the joint obtained by the liquid phase diffusion bonding method (crystal grain size exceeding the maximum grain size of 1 mm).
Furthermore, during the secondary bonding (liquid phase diffusion bonding) in the embodiment of the present invention, since it is not necessary to pressurize the joint surface during single liquid phase diffusion bonding or the applied pressure can be reduced, simple application is possible. It is possible to obtain a good liquid layer diffusion bonding portion only with the pressure jig. For this reason, according to the method of the present invention, liquid layer diffusion bonding with excellent joint quality that does not require the occurrence of welding defects and does not require advanced pressurization technology that uniformly pressurizes the joint surface at a high temperature at low cost. It can be realized.

  Therefore, it is possible to simplify the heat treatment such as QT required for further improving joint toughness in metal parts assembled by conventional liquid phase diffusion bonding, and to reduce the manufacturing cost as well as the productivity. It becomes.

  According to the embodiment of the present invention described above, it is possible to manufacture a joint joint of a metal material with high quality and high productivity as compared with a conventional joining method such as a single resistance welding method or a liquid phase diffusion joining method. However, as shown in FIG. 3, when at least one of the metal materials to be bonded is subjected to primary bonding (resistance welding) by abutting the end of the cylindrical metal material 11 with the other metal material 12, the following is performed. Therefore, in order to stably exhibit the effects of the present invention described above and stably improve the joint quality such as fatigue strength, it is preferable to use the embodiment described below. .

  That is, when primary joining (resistance welding) is performed by abutting the cylindrical metallic material 11 against the metallic material 12, as shown in FIG. 4 (cross-sectional view of FIG. 3), the pressure 14 and the thermal stress at the time of primary joining are used. The groove portion of the cylindrical metal material 11 opens in the outer surface direction 15, that is, in a trumpet shape, and the notch-shaped groove tends to remain on the open tip portion 13 on the outer surface side of the cylindrical metal material 11 after the primary joining. In the present invention, by the secondary bonding (liquid phase diffusion bonding) subsequently performed after the primary bonding, the unmelted amorphous alloy foil is further melted and flows into the notch-shaped groove remaining portion, thereby providing a conventional single resistance. Compared with welding, a notch-shaped groove remaining portion can be reduced. However, if the maximum remaining height 17 of the open tip after the primary joining becomes too large, it becomes difficult to obtain a smooth joint even if secondary joining is continued, and the notch tip of the groove remaining portion becomes a stress concentration part. This is not preferable because it causes a decrease in joint characteristics, particularly fatigue strength.

  In the present invention, in order to eliminate the above-mentioned problem when at least one of the cylindrical metal materials is primarily joined (resistance welding) and to improve the joint characteristics more stably, the following conditions should be further defined. Is preferred.

  FIG. 5 shows an inner surface side groove height A and an outer surface side groove of the cylindrical metal material with respect to the butt contact when the end portion of the cylindrical metal material 11 and the metal material surface are butted (not pressurized). The groove | channel sectional drawing for demonstrating the relationship between the height B, the distance C from a butt contact to an outer periphery, and the thickness t of the cylindrical metal material 11 is shown. In addition, the cross-sectional direction in this figure is a cross section that passes through the central axis of the cylindrical metal material 11 and is perpendicular to the joint surface.

  In the present invention, it is possible to prevent the groove portion of the cylindrical metal material 11 from opening in the outer surface side direction 15 by the applied pressure 14 and the thermal stress as shown in FIG. 4 during the primary joining of the cylindrical metal material 11 and the metal material 12. In order to reduce the maximum remaining height 17 of the open tip after the primary joining, the inner surface side groove height A and the outer surface side groove height B of the cylindrical metal material with respect to the butt contact 16 shown in FIG. The relationship between the distance C from the butt contact 16 to the outer periphery and the thickness t of the cylindrical metal material 11 is preferably set as an appropriate condition.

  FIG. 6 shows the ratio of the outer surface side groove height B to the inner surface side groove height A of the cylindrical metallic material before primary bonding (in a state where pressure is not applied), that is, B / A and the open tip after the primary bonding. The relationship figure with the maximum residual height 17 of a part is shown. The ratio of the distance C from the butt contact 16 to the outer periphery with respect to the wall thickness t of the cylindrical metal material 11, that is, C / t was 0.5.

  It can be seen that the maximum remaining height after the primary bonding can be sufficiently reduced under the condition that the value of B / A is 0.2 to 1. On the other hand, when the value of B / A is less than 0.2, the remaining height of the open end on the inner surface side of the cylindrical metal material 11 increases, and when the value of B / A exceeds 1, the cylindrical metal material 11, the remaining height of the open end portion on the outer surface side becomes large, and in any case, the maximum remaining height of the open tip portion after the primary joining becomes higher than 0.1 mm. In this case, it is difficult to sufficiently reduce the groove remaining portion of the joint portion by the repair action of the groove remaining portion by the secondary bonding (liquid phase diffusion bonding) performed after the primary bonding, which is not preferable. .

  Further, FIG. 6 shows the result obtained when the ratio of the distance C from the butt contact 16 to the outer periphery with respect to the wall thickness t of the cylindrical metal material 11, that is, the value of C / t is 0.5. Under the condition that the value of C / t is reduced to 0.5 or less, when the pressing force 14 is applied during the primary joining as shown in FIG. Since the outer surface side open tip portion is preferentially easily deformed by receiving the stress, the maximum remaining height of the open tip portion after the primary joining is further reduced. However, when the value of C / t is larger than 0.5, the open end on the inner surface side of the cylindrical metal material 11 is likely to be preferentially deformed when the applied pressure 14 is applied during the primary joining. Thus, even if the value of B / A is 0.2 to 1, it is not preferable because the maximum remaining height of the open tip after primary bonding cannot be reduced to 0.1 mm or less.

  Based on the above knowledge, in the present invention, when at least one of the metal materials is a cylindrical metal material, the end portion of the cylindrical metal material and the other metal material surface are brought into contact with each other for primary joining (resistance welding). In this case, the inner surface side groove height A and the outer surface side groove height B of the cylindrical metal material with respect to the butt contact, and the distance C from the butt contact to the outer periphery satisfy the following expression (1). Thus, it is preferable to form a V-shaped groove at the end of the cylindrical metal material. This makes it possible to stably and sufficiently improve the fatigue strength of at least one of the welded joints of the cylindrical metal material.

0.2 ≦ B / A ≦ 1 and C / t ≦ 0.5 (1)
Further, in the embodiment of the present invention, the maximum remaining height 17 of the open tip portion of the cylindrical metal material 11 after the primary joining (resistance welding) shown in FIG. 4 is continuously reduced as much as possible. In order to improve the fatigue strength of the joint more stably by reducing the unbonded remaining part of the open tip by melting and repairing the unmelted amorphous alloy foil during secondary bonding (liquid phase diffusion bonding). Is preferable. If the thickness of the amorphous alloy foil exceeds three times, it becomes difficult to improve the fatigue strength of the joint more stably by melting and repairing the unmelted amorphous alloy foil by secondary bonding. .

  Therefore, in the embodiment of the present invention described above, the maximum remaining height of the open tip portion after the primary joining is set to the amorphous alloy foil in consideration of the effect of melting and repairing the unmelted amorphous alloy foil by the secondary joining. It is preferable to make it 3 times or less of the thickness.

  In the embodiment of the present invention, when conditions such as the pressure 14 and the welding current at the time of primary joining (resistance welding) shown in FIG. 4 are not appropriate, primary joining of the cylindrical metal material 11 ( Even if the maximum remaining height of the open tip after resistance welding) is within the above-mentioned range, a bonded alloy layer in which the amorphous alloy foil is melted and solidified between the groove surfaces after primary bonding is uniformly formed. However, even if the vicinity of the butt contact is crimped, the crimping of the other groove surfaces becomes insufficient. In addition, there is a possibility that the bonded alloy layer may be separated before the secondary bonding due to the influence of the residual stress generated by the stress on the outer surface side of the cylindrical metal material 11 during the primary bonding (resistance welding).

  In order to suppress these problems, to form a uniform bonded alloy layer between the groove surfaces after primary bonding, and to form a bonded alloy layer with good adhesion that does not peel before secondary bonding, the above-described implementation of the present invention In the embodiment, it is preferable that the joint efficiency after the primary joining is 0.8 or more.

  In the embodiment of the present invention, the maximum remaining height of the open tip after secondary joining is as low as possible without increasing post-processing for improving the shape of the open tip. Since it can improve, it is preferable.

  In the embodiment of the present invention, the joint can be smoothed by melting and repairing the unmelted amorphous alloy foil at the time of secondary joining, but in order to further improve the fatigue strength of the joint, The maximum remaining height of the open tip is preferably 70 μm or less.

The effects of the present invention are illustrated by the following examples.
(Example 1)
Amorphous alloy foil for liquid phase diffusion having three kinds of chemical components of symbols A to C shown in Table 1 and a melting point, and steel, Ni alloy or Ti alloy having chemical components of symbols a to f shown in Table 2 Metallic mechanical parts were manufactured under the joining conditions shown in Tables 3 and 4 using the materials to be joined.
The obtained metal mechanical parts were subjected to a tensile test in the direction of separating from the joint surface and a Charpy impact test at 0 ° C. of the joint, and the joint strength and joint toughness were evaluated. Further, the amount of deformation of the metal machine part in the direction in which the joining stress was applied was measured, and the amount of deformation was also evaluated. The results are shown in Tables 3 and 4.
In Tables 3 and 4, the joint strength was evaluated by the ratio of the tensile strength of the joint joint to the tensile strength of the base material. When this value is 1, it means that the base material is broken, and when it is 1 or less, it means that the joint is broken. In addition, the evaluation of joint toughness was shown as “good” when the absorbed energy at 0 ° C. was 21 J or more, and “bad” when it was less than 21 J.

  In addition, No. 2-8 shown in Table 3 manufactured the metal machine component in the way as shown below. 7 and 8 show a T branch pipe inside by joining another branch pipe 2 to the branch port 4 formed in the upper surface of the central portion in the longitudinal direction of the internal pipe line 3 of the pipe body 1 having a square cross section. It is a schematic diagram for demonstrating the Example in the case of manufacturing the metal machine part for motor vehicles which has this. 7 is a perspective view of a metal machine part for an automobile, and FIG. 8 is a cross-sectional view that passes through the central axis of the branch pipe 2 and is perpendicular to the central axis of the internal conduit 3.

As shown in FIG. 7, the end portion of the branch pipe 2 that becomes the joint surface is preliminarily provided with a V-shaped groove having an angle of 45 ° by machining, and the joint surface between the groove 9 of the branch pipe 2 and the pipe body 1. And a ring-like liquid phase diffusion bonding alloy foil 5, and then a DC current is applied to the groove portion by the electrodes 7 and 10 that are in close contact with the branch pipe 2 and the pipe body 1, respectively, A pressurizing stress was applied.
The pressurizing stress was applied from above the branch pipe 2 through a stress transmission plate (not shown) that is hydraulically operated. As a result, the groove 9 of the branch pipe 2 is crushed and deformed until it becomes substantially equal to the thickness 8 of the branch pipe 2, and the liquid phase diffusion bonding interposed between the branch pipe 2 and the groove of the pipe body 1. Although the alloy foil 5 is once melted and solidified to form an alloy layer, since the joining time is extremely short, the non-isothermal solidified structure having an average thickness of 3 μm, that is, diffusion-controlled isothermal solidification has been completed. There was no so-called “brazing organization”. Next, as a secondary joining, the joining joint is heated to a reheating temperature of 1150 ° C. in an electric furnace having a high-frequency induction heating coil and a resistance heating element, and maintained for a predetermined time, thereby forming a joining alloy formed by the primary joining. After completing the isothermal solidification of the liquid phase diffusion of the layer, it was cooled.

  Further, Nos. 1 and 9 shown in Table 3 produced metal machine parts in the following manner.

  Two round bars having a diameter of 5 mmφ and a length of 50 mm were used as the materials to be joined, the open end surface was made completely I-shaped, and the groove surface roughness was ground to Rmax: 10 μm or less. An alloy foil for liquid phase diffusion bonding having a diameter of 5 mmφ was interposed between these grooves, and then a direct current was applied to the material to be joined, and simultaneously, a stress was applied to form a joint by resistance welding as a primary joint. After confirming that the concentricity of the round bars was not distorted, the joint having a length of 100 mm was secondarily joined, heated to a reheating temperature in an electric furnace having a resistance heating element, and then cooled. No subsequent heat treatment was performed.

  In addition, No. 10 and 11 shown in Table 4 show the comparative example which does not implement secondary joining (liquid phase diffusion joining), when manufacturing the said metal machine component, No. 12 and 13 are said metal machinery The comparative example which does not implement primary joining (resistance welding) when manufacturing components is shown. In addition, No. 14 shown in Table 4 performs primary joining (resistance welding) and secondary joining (liquid phase diffusion joining) when manufacturing the metal machine part, but the joining conditions are out of the scope of the present invention. A comparative example is shown.

  From the results shown in Table 3, No. 1 to 9 produced metal machine parts under the joining conditions within the scope of the present invention by the joining method of the present invention, the joint strength is always higher than the tensile strength of the base material. The deformation amount in the direction in which the joining stress was applied was 5% or less, and the use performance as a machine part was satisfactory. Further, since the holding time of the liquid phase diffusion bonding was short, the maximum crystal grain size of the joint was as fine as 500 μm or less, and the joint toughness was good.

  Nos. 10 to 14 shown in Table 4 are comparative examples that deviate from the range of joining conditions of the method of the present invention. No. 10 and No. 11 are comparative examples when only resistance welding is used. In this case, although No. 10 has an amorphous alloy foil for liquid phase diffusion bonding interposed, its structure is an unisothermal solidified structure. That is, since it is a brazed structure, the joint strength was lower than the base metal strength, the evaluation value was less than the reference 1, and fractured at the joint. In particular, No. 11 is only resistance welding in which an amorphous alloy foil for liquid phase diffusion bonding is not used, so that impurities and defects remain at the bonding interface, and the joint strength is reduced. In ordinary resistance welding, such an unstable joint strength may be obtained, and its defect detection is virtually impossible.

  Nos. 12 and 13 are comparative examples in which bonding is performed by applying a bonding stress of 5 MPa only by liquid phase diffusion bonding. In the comparative example of No. 12, although the joint holding time was shortened to 40 seconds, the crystal grains of the joint could be reduced, but the liquid phase diffusion joining was not completed at all, and thus the joint strength was reduced. . In the comparative example of No. 13, the retention time of the liquid phase diffusion bonding was increased in order to make up for the addition of resistance welding, but the joint strength was improved for that purpose, but the crystal grains of the metal structure became coarse. The absorbed energy at 0 ° C. was less than 10 J, and the toughness of the joint was lowered.

  In No. 14, the liquid phase diffusion bonding temperature in the secondary bonding was 820 ° C., which was lower than the conditions of the present invention, and did not reach the melting point of the amorphous alloy foil for liquid phase diffusion bonding. The formed brazing structure was further separated into a boride and a Ni-based alloy and became brittle, and the joint strength was separated.

(Example 2)
Next, No. 1 shown in Table 3 of Example 1 above. When the branch pipe 2 and the pipe body 1 shown in FIG. 8 are joined in the same manner as the present invention examples 2 to 8, as shown in Table 5, Table 6 and Table 7, the branch pipe which is a cylindrical metal material 2 under conditions where the thickness t and the like and the groove conditions of the branch pipe 2 at the time of butting (the inner surface side groove height A, the outer surface side groove height B, the distance C from the butt contact to the outer periphery) are changed. Bonded metal machine parts were manufactured, and mechanical properties of joints, particularly fatigue strength, were measured and evaluated. The chemical composition of the liquid phase diffusion amorphous alloy foil and the material to be joined is the same as in Example 1. Moreover, it carried out in the same way as Example 1 except the joining conditions shown in Tables 5 and 6.

The obtained metal mechanical parts were subjected to a tensile test and a fatigue test in the direction of separating from the joint surface, and the joint strength and joint fatigue strength were evaluated. The results are shown in Tables 6 and 7.
In Tables 6 and 7, the joint strength was evaluated by the ratio of the tensile strength of the joint joint to the tensile strength of the base material. When this value is 1, it means that the base material is broken, and when it is 1 or less, it means that the joint is broken. In addition, the fatigue strength of the joint is measured and evaluated by conducting an internal pressure fatigue test of the obtained metal machine part, and having no stress and cracking and fracture after a durability test of 10 million times (15 Hz) in a stress range of 20 to 200 MPa. Was evaluated as pass ○, cracked or broken, and rejected ×.

  No. 15 to 28 shown in Table 6 and No. 15 shown in Table 7. Nos. 29 to 32 each have a joint strength similar to that of the example of the invention shown in Example 1 by performing the primary joining (resistance welding) and secondary joining (liquid phase diffusion joining) defined in the present invention. The strength was higher than that of the conventional method, and the joint characteristics were excellent.

  Among these invention examples, Nos. 15 to 28 shown in Table 6 are performed within the scope of the present invention, while the groove condition of the cylindrical metal material defined in the more preferred embodiment of the present invention is the table. No. 7 shown in FIG. 29-32 are invention examples carried out under conditions that are outside the more preferred scope of the present invention.

  Nos. 15 to 28 shown in Table 6 are the inner surface side groove height A and outer surface side groove height B of the branch pipe 2 which is a cylindrical metal material, the distance C from the butt contact to the outer periphery, Since the relationship with the wall thickness t satisfies the conditions of 0.2 ≦ B / A ≦ 1 and C / t ≦ 0.5, which are more preferable conditions of the present invention, both joints have an internal pressure fatigue test. There was no subsequent failure, and excellent joint fatigue strength was obtained. Further, since the holding time of the liquid phase diffusion bonding was short, the maximum crystal grain size of the joint was as fine as 500 μm or less, and the joint toughness was good. Among these, any of the maximum remaining height of the open tip after primary joining, the joint efficiency after primary joining, and the remaining height of the open tip after secondary joining is more preferable in the present invention. Nos. 16-22, 24, and 26-28 within the range obtained results that the joint fatigue test was further improved as compared with Nos. 15, 23, and 25 where any of these preferable conditions was not satisfied. It was.

  On the other hand, Nos. 29 to 32 in Table 7 are all the inner surface side groove height A and outer surface side groove height B of the branch pipe 2, the distance C from the butt contact to the outer periphery, the thickness t of the branch pipe 2. This is an example of the invention in which the relationship with is deviated from the more preferable range of the present invention.

  No. 29 and No. 30 are cases where the groove height ratio B / A of the branch pipe 2 is larger than 1, that is, the groove height on the outer surface side is higher than that on the inner surface side. In this case, the groove on the outer surface side tends to remain due to the deformation that the outer surface side is originally high and the tube is slightly opened in the trumpet shape during resistance welding, and as a result of observing the joint cross section after resistance welding, As a result, the remaining height was increased to 100 μm or more, and the joint efficiency was also lowered. In No. 30, the position of the butt contact is close to the inner surface side, that is, C / t> 0.5, so that the groove on the inner surface side is preferentially deformed, and as a result, the open tip portion on the outer surface side. Remained largely.

  In No. 31, the groove height ratio B / A is within the scope of the invention, but the position of the butt contact is C / t> 0.5, and the inner surface side of the groove as in No. 30 Since the deformation concentrated on the outer surface, the open end portion on the outer surface side remained, and the remaining height increased to 100 μm or more.

  As a result of the above, Nos. 29 to 31 cracked at the number of times less than the predetermined number of repetitions due to cracks generated from the open tip on the outer surface side in the internal pressure fatigue test.

  No. 32 is an example in which the groove height ratio B / A is 0.2 or less, that is, the groove height on the inner surface side is five times or more the height of the groove on the outer surface side. In this case, the groove on the outer surface side was deformed during resistance welding, and the groove was in close contact with the end portion, but there was much remaining groove on the inner surface side, and the remaining height of the open tip portion was as large as 100 μm or more on the inner surface side. . As a result, in Comparative Example 32, in the internal pressure fatigue test, a crack was generated from the open tip portion on the inner surface side, and fractured at a number less than the predetermined number of repetitions.

(Example 3)
Next, as shown in FIG. 9, an embodiment in which the joining method of the present invention is applied when manufacturing hollow metal machine parts such as camshafts for various prime movers that have been conventionally manufactured by casting, forging, or the like. explain.

Using an amorphous alloy foil for liquid phase diffusion having two kinds of chemical components of symbols A and B shown in Table 1 and a melting point, and a material to be joined made of steel having chemical components of symbols a and b shown in Table 2 9 was produced under the following conditions under the joining conditions shown in Table 8.
That is, as shown in FIG. 9, a V-shaped groove having an angle of 45 ° is preliminarily applied to the end portion of the hollow metal material 18 to be a joint surface, and the groove 19 and the metal of the hollow metal material 18 are formed. After joining the joining surface of the material 20 through the ring-shaped alloy foil 21 for liquid phase diffusion joining, a direct current is applied to the groove 19 portion by the electrodes 22 and 23 respectively brought into close contact with the hollow metal material 18 and the metal material 20. The pressure stress 24 was applied simultaneously with flowing. The pressurizing stress 24 was applied from above the hollow metal material 18 through a stress transmission plate (not shown) that is hydraulically operated. As a result, the groove 19 of the hollow metal material 18 is crushed and deformed until it becomes substantially the same as the thickness 25 of the hollow metal material 18, and the liquid interposed between the grooves of the hollow metal material 18 and the metal material 20. Although the alloy foil 21 for phase diffusion bonding is once melted and solidified to form an alloy layer, since the bonding time is extremely short, an unisothermal solidification structure having an average thickness of 3 μm, that is, diffusion-controlled isothermal solidification is It was a so-called “brazing organization” that was not finished. Next, as a secondary joining, the joining joint is heated to the reheating temperature shown in Table 8 in an electric furnace having a high frequency induction heating coil and a resistance heating element, and held for a predetermined time, thereby forming a joining by primary joining. After completion of diffusion-controlled isothermal solidification of the alloy layer, the alloy layer was cooled.

The obtained metal mechanical parts were subjected to a tensile test in the direction of separating from the joint surface and a Charpy impact test at 0 ° C. of the joint, and the joint strength and joint toughness were evaluated. Further, the amount of deformation of the metal machine part in the direction in which the joining stress was applied was measured, and the amount of deformation was also evaluated. The results are shown in Table 8.
In Table 8, the joint strength was evaluated by the ratio of the tensile strength of the joint joint to the tensile strength of the base material. When this value is 1, it means that the base material is broken, and when it is 1 or less, it means that the joint is broken. In addition, the evaluation of joint toughness was shown as “good” when the absorbed energy at 0 ° C. was 21 J or more, and “bad” when it was less than 21 J.

  From the results shown in Table 8, Nos. 33 to 35, in which metal machine parts were produced under the joining conditions within the scope of the present invention by the joining method of the present invention, the average thickness of the joint layer after primary joining is 10 μm or less on average. The joint strength measured after the secondary joining always exceeded the tensile strength of the base metal. Further, the deformation amount in the joining stress application direction was 5% or less, and the use performance as a machine part was satisfactory. Further, since the holding time of the liquid phase diffusion bonding was short, the maximum crystal grain size of the joint was as fine as 500 μm or less, and the joint toughness was good.

The figure which shows the relationship between the thickness of the alloy layer formed by melt | dissolving and solidifying the amorphous alloy foil for liquid phase diffusion bonding, and the retention time until the isothermal solidification of the alloy layer is complete | finished. The figure which shows the relationship between the isothermal solidification retention time in the secondary joining (liquid phase diffusion joining) of this invention method, and joining joint strength. The perspective view which shows the embodiment in the case of butt-joining a cylindrical metal material and a metal material. A groove sectional view at the time of primary joining of a cylindrical metal material and a metal material. The groove | channel sectional drawing which passes along the central axis of the steel pipe before joining metal machine parts, and is perpendicular | vertical to a joining surface. The relationship figure of ratio (B / A) of the outer surface side groove height B with respect to the inner surface side groove height A of the cylindrical metal material before primary joining, and the maximum residual height of the open front-end | tip part after primary joining. The figure which shows the embodiment in the case of manufacturing a metal machine component by welding square cross-section piping and a branch pipe. The cross-sectional perspective view from the internal pipe-axis direction of square cross-section piping at the time of the assembly in FIG. The perspective view which shows the embodiment in the case of butt-joining a metal material and a hollow metal material. The groove | channel sectional drawing which passes along the central axis of the hollow metal material before joining a metal machine component, and is perpendicular | vertical to a joining surface.

Explanation of symbols

A: Groove height on the inner surface side of the cylindrical metal material relative to the butt contact
B ... Outside groove height of cylindrical metal material relative to butt contact
C: Distance t from butt contact to outer periphery ... Thickness 1 of cylindrical metal material ... Square section pipe main body 2 ... Branch pipe 3 ... Pipe inside pipe 4 ... Branch pipe 5 communicating from internal pipe to branch pipe ... Alloy foil 6 for liquid phase diffusion bonding ... Stress load direction 7 for primary bonding ... Electrode for resistance welding 8 on the branch pipe side ... Cross sectional shape 9 at the center of the branch pipe ... Groove 10 for resistance welding ... Electrode 11 ... Cylindrical metal material 12 ... Metal material 13 ... Opening tip 14 on the outer surface side of cylindrical metal material after primary joining ... Pressure 15 at the time of primary joining ... Outer surface side direction 16 ... Butt matching before primary joining Contact point 17: Maximum remaining height of open tip after primary joining 18 ... Hollow metal material 19 ... Groove 20 ... Metal material 21 ... Amorphous alloy foil 22 ... Electrode 23 ... Electrode 24 ... Pressure 25 at the time of primary joining ... Hollow metal material thickness

Claims (14)

  An amorphous alloy foil for liquid phase diffusion bonding is interposed on the groove surface of the metal material, and as a primary bond, the amorphous alloy foil and the metal material are melt-welded by resistance welding to form a joint portion. Then, as the secondary bonding, the joint portion is reheated to a temperature equal to or higher than the melting point of the amorphous alloy foil, and then liquid phase diffusion bonding is performed to hold and complete the solidification process of the joint portion. Liquid phase diffusion bonding method for metal machine parts.   2. The liquid phase diffusion bonding method for metal machine parts according to claim 1, wherein a holding time after the reheating is 30 seconds or more.   The composition of the amorphous alloy foil is based on Ni or Fe, and contains 0.1 to 20.0 atomic percent of one or more of B, P and C as diffusion atoms, V is contained in an amount of 0.1 to 10.0 atomic%, and the liquid phase diffusion bonding method for metal machine parts according to claim 1 or 2.   The resistance welding is a welding method of any one of energization heating type spot welding, projection welding, upset welding, and flash butt welding, and the amorphous alloy foil and the metal by the resistance welding. The method of liquid phase diffusion bonding of metal machine parts according to any one of claims 1 to 3, wherein the time of melt-welding with the material is 10 seconds or less. 5. The liquid phase diffusion bonding method for metal machine parts according to claim 1, wherein an amount of current in the resistance welding is 100 to 100,000 A / mm ² .   The metal according to any one of claims 1 to 5, wherein the pressure applied in the melt welding between the amorphous alloy foil and the metal material by the resistance welding is 10 to 1,000 MPa. Liquid phase diffusion bonding method for machine parts.   The metal machine according to any one of claims 1 to 6, wherein the thickness in the pressing direction of the non-isothermal solidified structure in the cross-sectional structure of the joint portion formed by the resistance welding is 10 µm or less on average. Liquid phase diffusion bonding method for parts. 8. The liquid phase diffusion bonding method for metal machine parts according to claim 1, wherein the joint efficiency of the joint portion formed by the resistance welding is 0.5 to 2.0. 9.
However, the joint efficiency is the ratio of the area of the groove surface of the metal material to the area of the joint part after the amorphous alloy foil and the metal material are melt-welded.   The metal according to any one of claims 1 to 8, wherein after the solidification process of the joint portion is completed, the joint portion structure is controlled by cooling at a cooling rate of 0.1 to 50 ° C / second. Liquid phase diffusion bonding method for machine parts.   A metal machine part comprising a joint formed by liquid phase diffusion bonding with a metal material, wherein the maximum grain size of the old γ crystal in the metal structure of the metal machine part as bonded is 500 μm or less Machine parts. At least one of the metal materials is a cylindrical metal material, and the inner surface of the cylindrical metal material with respect to the butt contact when the end of the cylindrical metal material and the other metal material surface are abutted to perform the primary joining A side groove height A, an outer surface side groove height B, and a distance C from the butt contact to the outer periphery satisfy the following expression (1). The liquid phase diffusion bonding method for metal machine parts according to claim 1, wherein a shape groove is formed.
0.2 ≦ B / A ≦ 1 and C / t ≦ 0.5 (1)
Where A is the groove height on the inner surface side of the cylindrical metal material, B is the groove height on the outer surface side of the cylindrical metal material, C is the distance from the butt contact point of the cylindrical metal material to the outer periphery, and t is the cylindrical metal material Represents the thickness of each material.   12. The liquid phase diffusion bonding method for metal machine parts according to claim 11, wherein the maximum remaining height at the open tip after the primary bonding is three times or less the thickness of the amorphous alloy foil.   13. The liquid phase diffusion bonding method for metal machine parts according to claim 11 or 12, wherein the joint efficiency after the primary bonding is 0.8 or more.   14. The liquid phase diffusion bonding method for metal machine parts according to claim 11, wherein the maximum remaining height of the open tip after the secondary bonding is 70 μm or less.

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